Staying Warm in Yukon

Staying Warm in Yukon

Staying Warm in Yukon

10 minute read – 

This is Part 1 of a 4 part series by guest author and ecologist, Joshua Robertson on how wildlife at the Yukon Wildlife Presere stays warm (thermoregulates) in the winter.

In the south of the Yukon, winter has long since settled in. Snow has accumulated, ice has formed, and daytime temperatures have regularly fallen below 0°C for many weeks. At most homes, winter coats have found their seasonal places at front doors, and skis and snowshoes now clutter entrance-ways and garages. Winter can be an exciting time of year for outdoor enthusiasts, fireside readers, and West Dawsonites alike (who can set aside their reliance on the George Black ferry for trips to town), and now is a great time to savour it.

Yet, hiding behind this winter enjoyment lies a sneaky and particularly interesting financial change; energy bills (or wood consumption, for those living off-grid) are steadily elevated. Yes, according to estimates made by Yukon Energy, monthly energy costs for the average home have risen by at least $75.00 since September. It may be several hundred dollars more if you use electric heat. Otherwise odds are good that your home heating bill has gone up significantly. These costs are certainly not small and emphasise a long-known and unfortunate reality for northerners; winter can be expensive. But, if you happened to complain about your rising energy costs to a local biologist, you might hear them say that you, human, should not feel so alone; it all depends on how you think about the word “energy”.

Energy is, at its simplest, the capacity to do work.

Throughout the duration of my PhD, I’ve found myself in many conversations about this ever-present and ever-charged word “energy”. To engineers, the term can stir thoughts of turbine velocities and kilowatt hours. To biologists, the topic most often brings up conversations about “ATP” (or, “adenosine triphosphate”), a molecule that is known to power most processes within a living cell. On the surface, both perspectives of what energy is or means might seem entirely different. If you ask an engineer or biologist for a definition of the word, however, you will probably receive the same, beautifully universal definition. Energy is, at its simplest, the capacity to do work. Whether the source is wind or complex proteins stored in a lynx’s breakfast, the potential to accomplish some task (such as twirling the blades of the Haeckel Hill wind-turbines or rebuilding damaged muscle tissue) remains fixed.

Now, with a clear definition of energy in mind, let’s return to that elusive and hypothetical suggestion made by our local biologist; winter has arrived, our energy bill is rising, but as humans, we aren’t alone in this experience. If energy is the capacity to do work, then what work is it that we and other animals require more of during the winter than other seasons? Although there may be a few answers to this  question, I’d argue that the most fitting one is probably the largest contributor to your monthly energy expenses this month: you guessed it, generating heat.

just as keeping warm comes with financial or time costs for humans, it also comes with energetic and nutritional costs for most other animals

For us humans, this typically means gathering wood, purchasing propane, or upping our electricity usage to keep our rooms comfortably warm throughout the short days and long evenings. For most other animals in the area (with a small caveat discussed below), generating heat means eating more and more often, shivering regularly, and hunting more frequently to warm their bodies through the processes of digestion and movement. So, just as keeping warm comes with financial or time costs for humans, it also comes with energetic and nutritional costs for most other animals; we pay in dollars, while the resident coyote pays in mice. An important thing to remember here is that maintaining a relatively constant and elevated body temperature is essential for survival for most animal species (ourselves included). That means that neither we nor they can easily or safely skimp on payments.

As you might expect, however, comparing costs of winter-living between us and our neighbourhood animals (in biology, we call them “sympatric” animals) isn’t so simple. As many readers may know, not all animal species are capable of producing body heat at the expense of food (a trait known as “endothermy”), and for those that are, the costs of doing so can vary quite dramatically. Thankfully, most all animal species that you’re likely to observe during a Yukon winter are indeed endotherms, so we can simplify our discussion by ignoring the other types (called “ectotherms”) from here on. Variability in the costs of keeping warm among species, however, is something we certainly can’t ignore. In fact, in my opinion, it’s in this variability where things truly become interesting. To help you side with me, take a look at the figure below that compiles energy consumption data collected by both Yukon Energy and a horde of poorly paid wildlife biologists.

Graph comparing energy consumption trends between Yukon species and average Yukon dwelling.

Because energy is surprisingly universal (as we discussed above) we can conveniently measure and display energy consumption for various animal species and a residential household using the same units (here, watts, or “W”: a measure of power). Before attempting to interpret this figure, first ignore the differences in vertical position of each line representing an animal species or household; these average differences in position are mostly explained by the (somewhat boring) differences in size among entities. Instead, take a close look at the overall differences between energy consumption in the cold (the far left) and the warmth (the far right) for each line/animal. These differences provide a fairly reliable measure of the relative costs of keeping warm for each species during cold months –  more commonly referred to as their costs of “thermoregulation”. Next, try considering the slopes of each line. As the inverse of our difference values, these slopes provide a reasonable indication of how efficiently heat is stored by a given species, where steep slopes represent relatively low heat-storage efficiency, and levelled slopes represent relatively high heat-storage efficiency.

Now, what you should have noticed is that for some species (the black-capped chickadee, black-billed magpie, and least weasel) the relative costs of thermoregulation in the cold can be quite high, and the relative heat-storage efficiency can be terribly poor. In chickadees, for example, costs of thermoregulation can reach over 70% of total energy expenditure on a given day, probably owing to their relatively poor ability to capture and preserve heat that is generated by their bodies (indicated by the steep slope of their line). More on chickadees here!

By contrast, for other species (the red fox and mule deer), the relative costs of thermoregulation in the cold can be shockingly low, and heat-storage efficiency shockingly high. The nearly-flat line associated with the red fox, for example, suggests that this species barely spends a mouse-worth of calories keeping warm at temperatures below -20°C, and is probably able to store most heat that is generated by its body. Furthermore, the curved line associated with the mule deer indicates that at temperatures above approximately 5°C, this species actually spends energy on getting rid of heat, not keeping warm, thanks to heat-storage efficiency being almost problematically high! Perhaps most impressively, however, is the average difference in slopes between animals and the residential home. From this difference, it appears that despite advanced insulation and/or double-brick walls, the relative costs of keeping our homes warm actually well-exceed those associated with many other animal species keeping themselves warm. Nevertheless, we should interpret household trends with caution given that use of electrical devices other than space-heaters or baseboard heaters (e.g. lights) may also increase in colder months, therefore further driving up total energy consumption.

At this point, you’re probably asking one of two questions:

  1. Why do we see such differences in costs of thermoregulation and heat-storage efficiency across animal species, or
  2. How do we, and not our houses, compare with these species for both traits?

These questions are something that Jake Paleczny (Executive Director at the Yukon Wildlife Preserve) and myself had been captivated by for quite some time. So, last winter, he and I equipped ourselves with an infra-red themographic camera and went to seek answers during a fortunately-timed cold snap at the preserve. 

Picture of Joshua Robertson at the Yukon Wildlife Preserve.

With our camera, we were able to remotely measure and quantify the amount of heat lost to the environment (again, in W) by both ourselves and the animals cared for at the preserve. From there, we were then able to compare relative heat-storage efficiency between different animal species and ourselves, and estimate just how much energy in food (measured by number of MacDonald’s cheeseburgers) we and other species might need to counterbalance energy lost in heat during the cold snap. Results of these estimations, will be detailed in the next post in this series, but for now, I’ll leave you readers with a few telling images (below) and a piece of a cheeseburger.

On the left is an infrared thermographic image of Jake that was captured while he was walking near the mule deer enclosure. The colours in this image represent the temperature of an object’s surface; the warmer the object, the brighter the colour (as indicated by the scale bar). To the right is a thermographic image of a thinhorn sheep (commonly known as a Dall sheep). The air temperature at which both images were taken averaged around -12°C – a modest winter day. Bear in mind that Jake is wearing a winter jacket and thermal lining underneath it, while the sheep is wearing its usual attire.

Now, if Jake were to have remained outside at the preserve for 4 hours, the amount of heat lost across his exposed face alone (the remainder of his body excluded) would amount to about a tenth of a cheeseburger. The thinhorn sheep? Well, we’ll have to get to that next time.

Joshua Robertson

Joshua Robertson

Behavioural and Physiological Ecologist

Joshua is a behavioural and physiological ecologist currently living on Cape Breton Island, Nova Scotia. During his PhD at Trent University, Joshua sought to understand how small birds can cope with the high costs of body temperature regulation when challenged with other environmental stressors (such as human and predator exposure). He is currently extending the research to better understand energy management strategies in warm-blood animals.

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Love for the Lynx

Love for the Lynx

Love for the Lynx

This story was originally published February 13, 2021 in the e-blast newsletter to Yukon Wildlife Preserve’s membership.

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While the ungulates have already gone through their languages of love the carnivores are just getting started!

It’s a great time to hear the courtship calls from the lynx, arctic fox and red foxes. While the two species of foxes are the same gender (red foxes – males, arctic foxes – females), our lynx group consists of a male and two females and all three lynx will remain in the habitat together this season.

In past years we have separated the male to eliminate breeding potential – an important practice to manage our animal collection and animal numbers. This year however the lynx will be left together to let nature take its course!

Our 3-legged male has never bred before nor has our younger female, who turns 7 this spring, so we do not have any history to give indication of sexual success. Our other female, who is now 13 years old, has successfully reared offspring in her younger days – most recently in 2014. If breeding is successful we could expect kittens in mid – late May. YWP collection growth and stability is a consideration for breeding given the age of our male, also 13 years. Further to that, BC Wildlife Park in Kamloops, a CAZA accredited facility, will also look to add to their population by accepting a litter of siblings. This potential breeding will be an important contribution to lynx genetics and the Species Survival Plan given how unique (completely unrepresented actually), his genetics are among captive populations.

It’s all up to the animals and only time will tell if these individuals are successful.

Lynx at Yukon Wildlife Preserve L to R:  3-legged male circa 2018 and kitten circa 2014.

All Photos credit:  Jake Paleczny

Lindsay Caskenette

Lindsay Caskenette

Manager of Visitor Services

Lindsay joined the Wildlife Preserve team March 2014. Originally from Ontario, she came to the Yukon in search of new adventures and new career challenges. Lindsay holds a degree in Environmental Studies with honours from Wilfrid Laurier University and brings with her a strong passion to share what nature, animals and the environment can teach us.


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Language of Love

Language of Love

Language of Love

15 minute read and listen –
With Valentine’s Day around the corner, we all have love on the brain… at least us humans do. Here at the Preserve the ungulates have already gone through their respective courtship rituals back in the fall. Nonetheless, it seems like a great time to talk about how male ungulates use their voices to attempt to secure reproductive success.

Have you heard the courtship calls of male ungulates at the Preserve? The male elk courtship calls, also known as bugles, are hard to miss. They are a high-pitched whistle that can be heard from kilometers away.1Murie, O.J. 1934. Elk Calls. Journal of Mammalogy, 13(4): 331-336 On the other hand, the male wood bison use soft purring during their courtship dance with females, a sound you have to be very close to hear.2Olson, W.E. 2020. The silent bison: differences in rut vocalizations between breeding age male plains and wood bison. Timbergulch PressWhat causes this variation in courtship sounds? Or, put another way, what are the selective pressures that shape the acoustics of male ungulate courtship calls?

To begin to answer this question, we need to know a little bit about how sound is produced. Figure 1 below and the explanation that follows summarize sound production, and highlight some important acoustic traits that vary across land mammal vocalizations in general.

Figure 1. On left: Elk vocal anatomy including the (A) lungs, (B) vocal folds, (C) vocal tract & (D) nostrils, lips, and tongue. On right: spectrograms of a (a) bear growl, (b) mule deer alarm snort, (c) male mule deer grunt, (d) male plains bison short roar, (e) mule deer fawn cry, (f) coyote howl, (g) elk alarm bark and (h) male elk bugle. The asterisk (*) shows the pitch of the mule deer fawn cry, which typically corresponds to the lowest horizontal line on the graph or the frequency difference between successive harmonics; the arrows (←) point to the harmonics, which, if clear, make a sound tonal. The bracket (}) indicates a lack of harmonics in the atonal mule deer alarm snort. Elk vocal anatomy3Frey, R., & Riede, T. 2013. The anatomy of vocal divergence in North American elk and European red deer. Journal of Morphology, 274: 307-319 drawn by Kelsey Saboraki.

Ungulates and other land mammals produce sounds4Fant, G. 1960. Acoustic Theory of speech production. Mouton, The Hagueusing a combination of their (A) lungs, (B) vocal folds, (C) vocal tract, and (D) their nostrils, lips, and tongue.5Frey, R., & Riede, T. 2013. The anatomy of vocal divergence in North American elk and European red deer. Journal of Morphology, 274: 307-319 Air is forced from the lungs past the vocal folds (A), which vibrate open and closed at a frequency related to their length and tension. Longer, looser vocal folds produce lower-pitched sounds, like the bear growl (a), whereas shorter, tighter vocal folds produce higher-pitched sounds like the mule deer fawn cry (e). Not all sounds an animal makes have a clear pitch. In other words, not all sounds are ‘tonal’. Some sounds are what we call atonal, or noisy, like the mule deer alarm snort (b). The difference is due to whether the vocal folds vibrate rhythmically to create a clear pitch (*), and give rise to clear harmonics (←) or not (}).
After air from the lungs passes through the vocal folds, it encounters the vocal tract (C), which is made of the esophagus, mouth, and nasal cavity. The shape of the vocal tract influences the timbre of a sound, or, a sound’s resonance frequencies. So, while the mule deer fawn cry (e) is close to the same pitch as the coyote howl (f), the resonance frequencies of these two sounds differ. The loudest parts of the mule deer fawn cry are the upper harmonics, while the loudest part of the coyote howl is closest to the pitch itself. You can clearly hear the difference if you listen to the two sounds, and see on the graph that the darkest (a.k.a. loudest) harmonics differ. The tongue, lips, and nostrils (D), as well as the position of the head and neck, can further modify a sound’s resonance frequencies by changing the shape of the vocal tract. The longer and wider the vocal tract is made to be, the lower the resonance frequencies.
The maximum duration or amplitude of a sound may have a lot to do with lung capacity, though similar to the pitch, a range of call durations and amplitudes are possible for a given species. That is, an elk can produce a short alarm bark (g), as well as a long bugle (h). Compare the elk bugle (h) with the mule deer grunt (c) and plains bison short roar (d) to get a sense of how these acoustic traits can vary across male ungulate courtship calls.
We now know how sounds are produced and how acoustic traits can vary across species, but how do these acoustic traits function when it comes to attracting mates? Let’s start by looking at the Theory of Honest Advertisement. This theory suggests that male courtship calls advertise a male’s body size, dominance, or overall fitness,6Reby, D., & McComb, K. 2003. Anatomical constraints generate honesty: acoustic cues to age and weight in the roars of red deer stags. Animal behaviour, 65: 519-530. with the idea being that the largest males are the most dominant and have the greatest success with the ladies.

Elk stag bugles, Yukon Wildlife Preserve.

Acoustically, we can think of this as male courtship calls being low in pitch and having low resonance frequencies, since larger animals should have longer vocal folds and a longer, wider, vocal tract. This is referred to as ‘allometric scaling’ and is the reason baby animals tend to have higher voices compared to adults (see the mule deer fawn cry (e) compared to the mule deer courtship grunt (c) in Figure 1). There is evidence to support the Theory of Honest Advertisement in plains bison. Plains bison courtship calls with lower resonance frequencies are made by males with larger body sizes, and males who have lower resonance frequencies in their courtship calls have greater mating success.7Wyman, M.T., et al. 2012. Acoustic cues to size and quality in the vocalizations of male North American bison, Bison bison. Animal Behaviour: 84: 1381-1391

Mule deer fawn and doe, Yukon Wildlife Preserve

However, conflicting evidence exists for the pitch of male courtship calls. Male elk courtship calls appear to straight up violate the idea of allometric scaling; the courtship calls made by adult male elk actually sound similar or higher in pitch than the cries of newborn elk.8Romanow, C.A. 2014. Designed to attract: the relationship of infant distress vocalizations to other social vocalizations. (Honours Thesis). University of Winnipeg So, while advertising size with low resonance frequencies may be important, there is definitely more to the story. Considering the variation in habitat preferences and in social systems across ungulates species, this shouldn’t be too surprising.

First and foremost, males need to ensure their courtship calls will actually reach the ears of potential mates. That is, we need to consider the venue in which males are making these sounds. If you take your date to a crowded restaurant, you want to be confident they are listening to you and only you when talking about your achievements. Just like ungulates that live in forests, you have to overcome direct physical barriers to your sound reaching your date. In the forest, trees and other vegetation more readily absorb or scatter high-pitched sounds than they do low-pitched sounds,9Marten, K., Quine, D., and Marler, P. 1977. Sound transmission and its significance for animal vocalization: II. Tropical Forest Habitats. Behavioral Ecology and Sociobiology, 2(3): 291-302. meaning high-pitched sounds may not travel very far or very clearly in this type of habitat. We might therefore expect forest-dwelling ungulates to use lower-pitched courtship calls. The low-pitched croaking of male moose is a good example of a forest-dwelling species whose courtship calls fit into this narrative.10Franzmann, A.W. 1981. Mammalian Species: Alces alces. The American Society of Mammalogists, 154: 1-7.

Moose Bull, Yukon Wildlife Preserve

Male ungulates also need to read the room. It would be overkill for your date to yell for your attention while you were having a nice quiet picnic, and the same is probably true for ungulate courtship. Mule deer males use low-amplitude, low-pitched grunting while engaged in a tending bond with a single female.11Geist, V. 1981. Behavior: adaptive strategies in mule deer. In: Mule deer and black-tailed deer of North America. Wallmo, O.C. (ed.). University of Nebraska, Lincoln. Pp 157-224. Contrast this with the literal screaming of a male elk attempting to entice an entire herd of females to stay in close proximity to him, and not to stray toward the lurking satellite males.12Murie, O.J. 1934. Elk Calls. Journal of Mammalogy, 13(4): 331-336 It seems reasonable that the social structure of ungulate species, in particular, their mating system type, would influence the acoustics of male courtship calls as well.

Finally, a discussion of male courtship sounds would not be complete without considering the target audience. We are not always sure if a male courtship call is meant specifically for a female, or whether it is a warning to potential rival males, or somehow a signal that targets both. In some cases, it is fairly clear the sound is meant for females – such as for wood bison males who purr only while engaged in a tending bond with a single female.13Olson, W.E. 2020. The silent bison: differences in rut vocalizations between breeding age male plains and wood bison. Timbergulch PressThe reaction of females or males to a courtship call may also suggest its function. For example, female elk tend to approach or at least alert to the high-pitched courtship calls of male elk.14Murie, O.J. 1934. Elk Calls. Journal of Mammalogy, 13(4): 331-336

It is widely accepted that tonal sounds (such as the mule deer cry (e) in Figure 1) are attractive to other animals, and atonal sounds (such as a mule deer snort (b) in Figure 1) are repelling to other animals.15Morton, E.S. 1977. On the occurrence and significance of motivation-structural rules in some birds and mammal sounds. The American Naturalist, 111(981): 855-869 If courtship calls of a given ungulate species are meant to entice females to approach or stay with a certain male, we might expect them to be tonal. Interestingly, the pitch of infant cries is known to be incredibly attractive to female ungulates,16Lingle, S., & Riede T. 2014. Deer mothers are sensitive to infant distress vocalizations of diverse mammalian species. The American Naturalist, 184(4). DOI: 10.1086/67767717Teichroeb, L.J., Riede, T., Kotrba, R., & Lingle, S. 2013. Fundamental frequency is key to response of female deer to juvenile distress calls. Behavioural Processes, 92: 15-23 so maybe the high pitch of male elk courtship calls grabs a female’s attention the same way an infant cry would.18Lingle, S., Wyman, M.T., Kotrba, R., Teichroeb, L.J., & Romanow, C.A. 2012. What makes a cry a cry? A review of infant distress vocalizations. Current Zoology, 58(5): 698-726.

Male ungulates vary vastly in their approach to attracting females: from the quiet, soft purring of the bison to the loud, high-pitched screaming of the elk, these males have successfully evolved to be heard by and attract respective females. This is pretty impressive given they have to deal with anatomical constraints, consider the environment they are calling in, the number of females they are calling to, and who else is around to hear them. We still don’t have a full understanding of how these different factors have shaped male ungulate courtship calls, and there are even some species we have yet to learn about: mountain goats, thinhorn sheep and woodland caribou to name a few; animals that are tricky to study in the wild.

L to R:  Rebecca making a sound recording of moose at Yukon Wildlife Preserve; Cora making a sound recording of elk at Sandy Hills Elk Ranch.

The focus of my (Cora’s) Master’s thesis is to look at courtship calls from a diverse group of ungulate species that vary in their size, habitat, and mating system type, and to construct models to see which of these factors most readily correlates with the particular acoustic traits that make up the courtship calls. I will also compare the tonality and pitch of a species’ newborn cries with the tonality and pitch of male courtship calls. To do this properly, we require a large data set. Luckily, my good friend and colleague Rebecca Carter is set up with recording equipment that she will use to try and capture some of the courtship calls from ungulates at Yukon Wildlife Preserve. These recordings Rebecca collects will be combined with the elk courtship calls I recorded for my undergraduate thesis, and a library of courtship calls that my supervisor, Dr. Susan Lingle, has amassed through the years as well. I am also scouring the scientific literature for courtship calls of species we do not have access to.

Stay tuned for the results of this research, and remember that size probably isn’t the only thing that matters.

Would you like to contribute to this research? Do you have video or audio recordings of ungulate courtship calls that you’d like to share? We are in need of certain species that are tough to observe in the wild, but welcome the sounds of any ungulate. If you are interested, please email Thank you for you interest!

All sound clips credit Lingle Lab:  Dr. Susan
Lingle’s Lab at the University of Winnipeg, with the exception of Grizzly Bear19 and Mule Deer grunt 20

Cora Romanow & Rebecca Carter

Cora Romanow & Rebecca Carter

Masters Student & YWP Wildlife Interpreter

Cora and Rebecca share a love for wildlife, nature, and sneaking up on and observing deer. They bonded over these shared loves back in Manitoba and on the Alberta grasslands while working in the same behavioural ecology lab, and remain passionate about animals; Cora completing her Masters in animal communication and Rebecca a wildlife interpreter here at the Preserve. Together they strive to make wildlife research accessible and relatable (and at times humorous) to inspire others to also love the natural world.

Kelsey Saboraki

Kelsey Saboraki

Artistic Illustrations - Elk Anatomy Figure

Kelsey Saboraki is a keen observer of the natural world and her scientific illustrations reflect this. Her attention to detail is accompanied by an appreciation for the whole and this balance breathes life into even the most technical of diagrams. For inquiries, contact

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Leaps and Bounds “Winter is Here”-Lynx

Leaps and Bounds “Winter is Here”-Lynx

Leaps and Bounds “Winter is Here”-Lynx

9 minute read – “Winter Is Here” series continues with the elusive enigma – Lynx!

I, for one, love winter. What a unique time of year it is to be able to get outside in the short but cherished sunlight hours or total darkness for a hike, ski, or skate, then get inside and warm up by a fire. Of course Yukon’s wildlife call the outdoors their home but don’t worry they are just fine outside.

With those view-blocking leaves off the trees and the snow piled high, the Preserve’s most elusive resident – the lynx, becomes ever so slightly easier to spot in their habitat.

The lynx is one of Yukon’s only cat species other than the even more secretive cougar.1Government of Yukon. 2021. Cougar.  Lynx can be found in the boreal forest right across Yukon, Alaska, and still occupy roughly 95% of their historic range in Canada.2Poole, K.G. 2003. A review of the Canada lynx, lynx canadensis, in Canada. Canadian Field-Naturalist 117(3): 360-376.  Here in the subarctic boreal forest lynx have adapted to thrive in even the coldest, harshest winters Yukon could throw at them, while also keeping up with their favourite prey: the snowshoe hare.

Lynx almost exclusively prey on snowshoe hares during the winter months, as hares make up anywhere from 75-90% of a lynx’s diet on average.3Ivan, J.S., & Shenk, T.M. 2016. Winter diet and hunting success of Canada lynx in Colorado. The Journal of Wildlife Management 80(6): 1049-1058.In the summer and when hare populations are low, lynx will turn to other small animals like red squirrels, mice, and ptarmigan4Poole, K.G. 2003. A review of the Canada lynx, lynx canadensis, in Canada. Canadian Field-Naturalist 117(3): 360-376., but those hares are by far the preferred ones to catch. So much so that the number of lynx there are in an area depends on the number of hares.5Poole, K.G. 2003. A review of the Canada lynx, lynx canadensis, in Canada. Canadian Field-Naturalist 117(3): 360-376. This is one of the most well recorded examples of a predator-prey interaction dating back to the mid-1800’s.6MacLulich, D.A. 1937. Fluctuations in the numbers of the varying hare (Lepus americanus). University of Toronto Studies Biological Series 43. University of Toronto Press, Toronto

Figure 1. Population cycles of lynx and snowshoe hare over a 90-year period from the fur-trapping records of the Hudson’s Bay Company. Figure based on data from MacLulich (1937) and Elton and Nicholson (1942)

Snowshoe hare populations are cyclic: they peak about every ten years then crash shortly thereafter. Lynx follow this pattern lagging about 1-2 years behind the hares.74. Boutin, S., et al. 1995. Population changes of the vertebrate community during a snowshoe hare cycle in Canada’s boreal forest. Oikox 74: 69-80. 8MacLulich, D.A. 1937. Fluctuations in the numbers of the varying hare (Lepus americanus). University of Toronto Studies Biological Series 43. University of Toronto Press, Toronto  Hares are rich in nutrients providing lynx with the necessary energy and fat reserves needed to survive the long, cold winters. When hare populations are booming, lynx have better survival rates and females can support more kittens to adulthood. An abundance of food and high reproduction rates increases the lynx’s population density to 30-45 lynx/100 km2 , but once the hare numbers decline, that lynx population density drops down to just 2 lynx/100 km2 in the same region.9Poole, K.G. 2003. A review of the Canada lynx, lynx canadensis, in Canada. Canadian Field-Naturalist 117(3): 360-376.

To keep up with the snowshoe hare – a specialist of the subarctic and arctic ecoregions, lynx have to survive and thrive alongside them in these colder lands.

Another great thing about winter is that the snow is a great record keeper of all the different critters that have wandered through an area. Keep an eye out for rounded paw prints indicative of the lynx. Compared to their body size, lynx have huge paws and can spread their fur-covered toes apart making the surface area even larger. Just like a pair of snowshoes on our feet, these giant paws help the lynx walk on top of packed snow. Along with their long legs these cats can wade through soft, deep snow with ease and use their larger back legs to help power big leaps either up trees or when bounding to catch up to a hare.10Murray, D.L., & Boutin, S. 1991. The influence of snow on lynx and coyote movements: does morphology affect behavior? Oecologia 88(4): 463-469.

Lynx can be found across Yukon in the boreal forest, but the slight difference of how open or dense that forest is will change how the lynx behaves while hunting. If lynx are in more open areas with less vegetation on the ground to hide in, their tactic is to chase hares. However, this method is not very successful since lynx cannot keep pace with hares over long distances.11Murray, D.L., Boutin, S., O’Donoghue, M., & Nams, V.O. 1995. Hunting behaviour of a sympatric felid and canid in relation to vegetation cover. Animal Behavior 50: 1203-1210.  More often lynx are ambush hunters, lying in wait in bed-sites along well-used hare trails until the prey comes close.12Poole, K.G. 2003. A review of the Canada lynx, lynx canadensis, in Canada. Canadian Field-Naturalist 117(3): 360-376. To be successful, lynx prefer old growth forests with an abundance of spruce and pine cover along with fallen trees and dense vegetation to hide in.13Murray, D.L., Boutin, S., O’Donoghue, M., & Nams, V.O. 1995. Hunting behaviour of a sympatric felid and canid in relation to vegetation cover. Animal Behavior 50: 1203-1210. This tactic of staying still and ambushing unsuspecting prey not only provides more energy rich food for the lynx, it also allows them to conserve precious energy needed to keep their body temperatures warm during the winter.

When you’re staying still, having a warm coat on also helps you to retain heat against the cold winter air. Lynx have a very thick winter coat made up of a fluffy underfur that traps air against the skin creating an insulating barrier. The soft underfur is covered in coarse guard hairs that function as a waterproofing layer preventing snow and ice from reaching the skin underneath, just like how our waterproof, puffy winter coats function. Lynx’s winter coats are a light grey colour, mottled with those guard hairs that break up the cat’s outline allowing them to blend in to the grey and white forest background. In contrast, the summer coat is shorter with more reddish brown in colour; again allowing the cats to sneak around the forest undetected.14Vaughan, T.A., Ryan, J.M., & Czaplewski, N.J. (2015). Mammalogy. (6th ed.). Burlington, MA: Jones & Bartlett Learning.

Lynx are considered to be almost entirely solitary animals especially in the heart of winter after that year’s kittens have dispersed from the den. Adult lynx usually only pair up for a brief time in late February or March for the breeding season then separate again.15Poole, K.G. 2003. A review of the Canada lynx, lynx canadensis, in Canada. Canadian Field-Naturalist 117(3): 360-376. However, new radio-collar data out of Kluane National Park shows lynx pairing up and eating the same kill together; behaviours that indicate these cats may be more social than previously thought, at least in the Kluane region.16Morin, P. (2020, December 29). Not so solitary: Lynx links surprise scientists. Retrieved from: This is fascinating new data that right now really leaves us with more questions than answers. Have lynx always been more social than we thought and we just didn’t notice or is this new behaviour in response to change? Currently, we are in a period of low snowshoe hare populations and declining lynx numbers17Krebs., C.J., et al. (2020). The Community Ecological Monitoring Program annual data report 2019. Retrieved from: so perhaps this is evidence of cooperation either between relatives like parents and offspring or siblings, or between unrelated individuals in order to survive.18Morin, P. (2020, December 29). Not so solitary: Lynx links surprise scientists. Retrieved from:

 Lynx are a truly remarkable species and being so elusive, we continue to uncover new things about them and their behaviour.

Winter continues on here in the Yukon but it really is the best season to bundle up and get outside for your chance to spot a lynx sneaking through the bare trees or even just their round, furry prints travelling on top of the snow. If you are lucky enough to spot a lynx either out in the wild or right here at the Preserve (there are three of them) take note of their winter adaptations: large paws, long legs, thick fur coat covering their entire body, and stealthy behaviour; all traits that make them such successful felines of the north!

All Lynx photos credit to L. Caskenette

Rebecca Carter

Rebecca Carter

Visitor Services Coordinator

Rebecca joined the Wildlife Preserve in the summer of 2020 after moving from Manitoba to the beautiful and wild Yukon. Rebecca earned a degree in Biology with honours from the University of Winnipeg studying behaviour in mule deer (one of her top 20 favourite animals.. it’s hard to choose!). She loves connecting with others through nature and sharing stories and knowledge about the animals at the preserve with visitors.


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